The sensitivity of diagnostic system to the changes of the set of measuring signals

The problem of sensitivity of a diagnostic system to the variations of the set of accessible measuring signals is discussed. These variations are the consequences of faults or switch-offs by the operator of the sensors, which occur during an operation of the diagnostic system. It leads to the changes of the set of executed diagnostic tests. These changes affect the achieved diagnosing accuracy. The formalized descriptions of the object of diagnosis and the diagnostic system are defined. The measures of diagnosing accuracy in the cases of single faults are introduced. The indexes of sensitivity of diagnostic systems to the changes of the set of measuring signals are also introduced. The above consideration has been illustrated by a practical example of the diagnostic system for the evaporator in a sugar factory